Quickly toast the chile by turning it an inch or two above an open flame
for a few seconds, until its aroma fills the kitchen. (Lacking an open
flame, toast it in a dry pan over medium heat, pressing it flat for a
few seconds, then flipping it over and pressing it again.) Break the
chile into pieces and put in a blender, along with the tomatoes with
their juice. (A food processor will work, but it won't completely puree
the chile.)

Everytime I make this, I wish I'd done this step first...the onions can cook while you are toasting and pureeing the chile and tomatoes. Heat the oil in a large (4 quart) saucepan over medium-high. Add the
onion and garlic and cook, stirring frequently, until golden, about 7
minutes. Scoop up the onion and garlic with a slotted spoon, pressing
them against the side of the pan to leave behind as much oil as
possible, and transfer to the blender; set the pan aside. Process until
smooth.

Return the pan to medium-high heat. When it is quite hot, add
the puree and stir nearly constantly until thickened to the consistency
of tomato paste, about 6 minutes. Add the broth and epazote if using.
Reduce the heat to medium-low and simmer for 15 minutes. Taste and
season with salt, usually about a generous teaspoon (depending on the
saltiness of the broth).

Just before serving, add the chicken to the simmering broth. Divide the
avocado, cheese and tortilla chips among the serving bowls. When the
chicken is done, ususally about 5 minutes, ladle the soup into the
bowls. Pass the lime separately. Rotisserie or grilled chicken can stand
in for the raw chicken breasts (add it at the last second). I add the corn, beans and chicken right before serving and just heat til warm.

We like it with sour cream, cheese, and avocado and of course tortilla chips. Also, the first time I made this I pretty much assumed my kids wouldn't eat it. I thought it would be too spicy or they'd think it was weird, but everyone ate it and loved it (even Calvin). It's really just a chicken taco soup. Here's a time saving tip...whenever I make this soup, I double the ingredients up until I blend everything (the tomatoes, chili, onions, garlic). Then I divide the mixture in two, put one part in the pot and the other part in the freezer. I don't recommend reducing both mixtures at once, it takes a long time and splatters all over the kitchen making a mess, and almost making this a non time saver. But when you have a busy day, and need an easy meal, all you have to do is pull the mixture out of the freezer pop it in your pan, reduce it and add the broth, chicken (and beans and corn if you are me)...I always make this on a day that I go to the store, so I always buy a rotisserie chicken. Easy peasy.